In the United States, over 40,000 very low birth weight (VLBW) infants are born each year, many of whom are critically ill and require care in neonatal intensive care facilities. Invariably, most infants of less than 1,500 grams receive blood transfusions. The use of red cell transfusion is an invaluable part of the care for these infants. Such transfusions are particularly needed for exchange transfusions in treating either hemolytic disease of the newborn or hyperbilirubinemia. More commonly, such transfusions are for treating anemia due to physiologic changes and routine phlebotomy, since such procedures often impair already suppressed cardiorespiratory function.
Most very low birth weight (VLBW) infants receive red blood cell transfusions during the first four weeks of life. A recent study revealed that in 22 transfused neonates, each received an average of 2.5 homologous CPDA-1 RBC transfusions (range 1 to 11), having a mean volume of 16 ml and received a mean total transfusion volume of 60 ml. Transfusions are administered primarily to replace losses due to diagnostic sampling. The need for frequent monitoring of blood gasses and electrolytes, the small blood volumes of these infants (100/kg), and limitation on total volume administered at one time (10 cc/kg/transfusion), result in repeated exposure of these infants to the risks of homologous red blood cell transfusions. Results of another study indicate that an average homologous blood exposure rate of 6.9 (range 1 to 25) different donors in 52 neonatal intensive care unit infants. Seventy percent of infants present in their unit received transfusions during the study period.
In a recent study conducted at State University of New York at Syracuse, in the neonatal intensive care unit, 55% of VLBW infants born during a one-year period received a red cell transfusion; of these 86% experienced at least three transfusion episodes during the first month of life. Studies evaluating the rate of homologous blood donor exposures in neonates have documented exposure ranges of 2.4 to 10 different source exposures per neonate. The benefits of autologous transfusion in the adult population have been demonstrated, minimizing the risks of transfusion transmitted diseases associated with the homologous blood supply. These risks, including those associated with CMV infection, are of critical concern in the ill, premature neonate.
The placenta, usually discarded after birth, contains a reservoir of the infant's own blood representing an ideal source of autologous blood. Over the past ten years a few centers have used autologous blood obtained from placentas, transfusing the blood immediately following birth to volume-resuscitate newborns. Prior studies have documented the bacteriologic safety and proof of anticoagulation of placental blood harvested in heparinized containers. However, there are no known studies examining the safety and practicality of the extended storage of autologous placental blood for use in infants during the first month of life.
Although many blood banking techniques and approaches specifically addressing the needs of the small infant have been developed, most concerns are related to the handling of small blood volumes, minimizing donor blood wastage, and avoiding obvious risks of homologous blood exposure such as CMV transmission and graft versus host disease. Although the use of quadruple or "cow" packs allow for multiple transfusions from a single unit, this does not satisfactorily solve the problem of multiple donor exposures during the week to month long period of the infant's transfusion dependency.
Other suggested methods of minimizing infant exposure to multiple blood donors include the concept of the "walking donor" in which small volumes of blood are withdrawn from a donor as needed by the infant, frozen rbc aliquots from a single unit to be used by a designated infant, and creative uses of a sterile docking devise which would allow for the aseptic "closed" removal of blood aliquots from a donor unit, thereby maintaining the storage period and availability of the unit. To date, none of these concepts have proven practical for use in the transfusion dependent neonate. Although the treatment of neonatal anemia with recombinant erythropoietin would appear promising, several small studies evaluating this approach have shown little success.
Autologous fetal blood collected from the placenta has been used for volume resuscitation of the newborn in the delivery room for over ten years. Various studies have demonstrated that placental blood can be collected and adequately anticoagulated into heparinized containers for use within the first 12 hours of life. If transfused immediately, the autologous blood has been shown to have minimal bacteriologic risks. To date, there have been no studies evaluating the safety and practicality of collecting and storing placental blood for subsequent autologous transfusion during the first month of life. There is also little data on the hematologic and biochemical changes of fetal blood stored in CPDA-1 preservative banking placental blood by studying a new method of collection, and evaluating the bacteriologic safety, the adequacy of anticoagulation and the conditions for maintaining optimal red cell viability during storage.